Selenium is an essential mineral that, although needed in small amounts, plays a major role in supporting the body's antioxidant system and immune function of fish. This study aims to evaluate the effect of adding organic selenium to feed on growth performance, protein retention, fat retention, blood profile, and antioxidants of climbing perch. This study used a completely randomized design with 4 treatments and 3 replications. The treatments were four doses of organic selenium added to the feed, namely 1, 2, 3, and 4 g Se/kg feed. The climbing perch used has a weight ranging from 3.2-4.4 g and a length ranging from 4.2-5.8 cm. The fish were kept in an aquarium measuring 40x30x30 cm3 with a density of 10 fish/aquarium. The fish were kept for 45 days with a feeding frequency of 2 times a day as much as 5% of the total weight of the fish. The results of this study indicate that climbing perch fed with feed containing 1 g Se/kg feed showed growth performance, and could improve hematological parameters and strengthen the antioxidant system of climbing perch.